A few design questions...

mzimmers

OK, I did it from Creator. "Run qmake" returned this:

@Running build steps for project simulatorGUI...
Starting: "/usr/bin/qmake" /Users/mzimmers/wideband/SoC simulator/simulatorGUI/simulatorGUI.pro -r -spec macx-g++ QMLJSDEBUGGER_PATH=/Developer/Applications/Qt/Qt Creator.app/Contents/Resources/qml/qmljsdebugger
The process "/usr/bin/qmake" exited normally.@

And the build returned a whole bunch of stuff that I won't bother putting here (unless you really want it), but it did build successfully this time. And I checked the build directory, and I now have files for the filter there.

Now, in the UI, the value displays as "undefined." And, I'm getting a couple run-time errors about "no such signal." One is on this line (in soc.cpp):

@ connect (this, SIGNAL(shaperOutIChanged()), this, SIGNAL(shaperOutIStringChanged()));
@

And the other is (in widget.cpp):
@ connect (soc, SIGNAL(shaperOutIChanged()), this, SLOT(updateShaperOutI()));
@

ZapB

OK. For some reason then the build system had not noticed that qmake needed to be re-run. But at least it is fixed now.

For the signals...

The first connect statement should now be moved into the DemodShaperFilter class since that is where we have all of the Qt property stuff now.

The second statement should be changed to something like this:

@
connect (soc->demodShaperFilter(), SIGNAL(shaperOutIChanged()), this, SLOT(updateShaperOutI()));
@

where you need to add:

@
DemodShaperFilter* demodShaperFilter() const { return m_demodShaperFilter; }
@

to your Soc class. Note that I have used "m_demodShaperFilter" but I have not seen your Soc.h header file so you'll have to replace that with whatever you called your pointer to the DemodShaperFilter object.

That should remove those runtime warnings.

Incidentally, I find it useful to run with the environment variable QT_FATAL_WARNINGS=1 set. With that in place any runtiem warnings form Qt will cause your app to abort at that point which the debugger will catch so that you can inspect the stack trace. You can set the above in the Qt-Creator project settings under the RunTime Configuration tab.

mzimmers

OK. I'd already copied the first connect into the DSF, but hadn't removed it from the Soc. Now done.

About the second one: something doesn't look right with that function definition. Either the type or the return value needs to be changed to agree with the other...

EDIT: also, the "const" was causing the compiler to beef, so I removed it.

And, at runtime, I now get this error:

@qrc:/DemodShaperFilter.qml:15:2: QML Connections: Cannot assign to non-existent property "onShaperOutIChanged"@

I didn't change my qml file; here it is:

@import QtQuick 1.0

Rectangle {
id: myRect
width: 300
height: 100
color: "#808080"

Text {
text: "shaperOutI = " + soc.shaperOutIString;
font.pointSize: 20
anchors.centerIn: parent
}

Connections {
target: soc
onShaperOutIChanged: {
if (myRect.color == "#808080")
myRect.color = "#c0c0c0"
else
myRect.color = "#808080"
}
}
}

@

Do I change the target from soc to something else (like the DSF)?

mzimmers

I cleaned up some stuff, but I'm still getting this error message:

bq. qrc:/DemodShaperFilter.qml:15:2: QML Connections: Cannot assign to non-existent property "onShaperOutIChanged"

Any suggestions?

ZapB

Can you post he header file of your DemonShaperFilter class, the place where you expose that object to the qml context and the QML file please?

mzimmers

Hi, Zap -

Apart from some include files, and constant definitions, what I posted above is my complete header file for that class. I thought I copied everything necessary over from the original Soc class; did I miss something?

ZapB

What about the part where you expose the object to the QML context? Also can you show how you get the pointer to the DemodShaperFilter object from the Soc object please? You mentioned something about not being able to use const or a pointer or something there?

mzimmers

The Soc class has a public function to return the address of the DSF object:

@ DemodShaperFilter* demodShaperFilter() { return &filter; }
@

I'm not sure I remember "exposing" the DSF to QML. In my .qml file, there's a Connections block:

@ Connections {
target: soc
onShaperOutIChanged: {
if (myRect.color == "#808080")
myRect.color = "#c0c0c0"
else
myRect.color = "#808080"
}
}
@

But I didn't see any code in my Soc class that tied the object to QML.

ZapB

Somewhere we had something like:

@
view->rootContext->setContextProperty( m_soc, "soc" );
@

which should now become something like:

@
view->rootContext->setContextProperty( m_soc->demodSHaperFilter, "dsf" );
@

then in your QML scene replace all references of "soc" to "dsf".

mzimmers

Oh! That's in the widget constructor:
@Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget),
m_timer(new QTimer(this)),
soc(new Soc(this))
{
ui->setupUi(this);

connect (m_timer, SIGNAL(timeout()), soc, SLOT(runOneCycle()));

connect (soc->demodShaperFilter(), SIGNAL(shaperOutIChanged()), this, SLOT(updateShaperOutI()));

QDeclarativeView* view = ui->declarativeView;

view->rootContext()->setContextProperty("soc", soc);
view->setSource(QUrl("qrc:/DemodShaperFilter.qml"));

m_timer->start(200); // 200 ms delay between cycles (for now)
}
@

And, by "QML scene," you're referring to the .qml file?

ZapB

Yes that is what I meant. You need to make the changes that I mentioned to that line ie:

@
view->rootContext()->setContextProperty( "dsf", soc->demodShaperFilter() );
@

and in your QML file replace all mentions of "soc" with "dsf". It should work then.

mzimmers

OK, we're getting somewhere. I no longer get the error message at startup, and the QML window now comes up with the correct initial value of the variable. But...it's not updating. I have this line in my cycle loop for the object:

@ emit shaperOutIChanged();
@

Which I believe should correspond with this line in my DSF constructor:

@ connect (this, SIGNAL(shaperOutIChanged()), this, SIGNAL(shaperOutIStringChanged()));
@

So, I'm not sure what's missing.

Also, I'm confused about something: why is it we're still using some Soc functions for our QML processing?
@ ui->setupUi(this);

connect (m_timer, SIGNAL(timeout()), soc, SLOT(runOneCycle()));

connect (soc->demodShaperFilter(), SIGNAL(shaperOutIChanged()), this, SLOT(updateShaperOutI()));

QDeclarativeView* view = ui->declarativeView;

view->rootContext()->setContextProperty("dsf", soc->demodShaperFilter());
view->setSource(QUrl("qrc:/DemodShaperFilter.qml"));

m_timer->start(200); // 200 ms delay between cycles (for now)
@

Thanks.

ZapB

Where do you emit the shaperOutIChanged() signal? Can you post that snippet of code please? Have you run it in a debugger to make sure that emit is actually called? Do you get any runtime warnings on the console output?

Can you also post the qml file where you use this property please - although it sounds as if the QML is correct since you get an intiial value. Just sounds like the signal is not being emitted correctly which would trigger the QML engine to update the displayed value.

The only reason we are referring to the soc object is that it is the only way we can get at the pointer to the DemodShaperFilter object. Are you using it anywhere else in relation to displaying stuff in the GUI?

mzimmers

The shaperOutIChanged() signal is (currently) in the test loop for the DSF class. It loops 1024 times, processes the object and then executes this line (within the loop):

@ emit shaperOutIChanged();
@

This routine is the one automatically generated within Qt, right?

Contents of the .qml file:

@import QtQuick 1.0

Rectangle {
id: myRect
width: 300
height: 100
color: "#808080"

Text {
text: "shaperOutI = " + dsf.shaperOutIString;
font.pointSize: 20
anchors.centerIn: parent
}

Connections {
target: dsf
onShaperOutIChanged: {
if (myRect.color == "#808080")
myRect.color = "#c0c0c0"
else
myRect.color = "#808080"
}
}
}

@

The string is the conversion of the display value. As a reminder, we did this for formatting convenience. I copied all of that code directly from the Soc class to the DSF.

And no, I don't believe the DSF object is being used anywhere else for display purposes. The Soc invokes the DSF test loop, and that's about it.

Thanks...

mzimmers

Hi, Zap -

I did some more debugging. The internal logic is definitely working; that is, the loop is clearly executing and the emit statement appears to be called 1024 times. Where would you suggest I look next for the disconnect here?

Thanks.

ZapB

Sorry for the delay, I must have missed the notification email. I'm not sure without seeing the source code. Are you able to zip it up and mail it to me so that I can take a look (I can sign an NDA if needed). Alternatively boil it right down to a very simple example that still shows the problem and send me that zip file.

mzimmers

I can zip up the relevant files and send them to you, if I had a real email address for you. You can provide it via a message if you like.

Thanks.

ZapB

Sent you my email address via private message.

mzimmers

Replied. Thanks a ton, Zap.

ZapB

OK. sorted it. I'll send the corrected file to you by email but explain it here.

Firstly in your loop in void DemodShaper::testCycle() you were emitting the signal as you said. However, you were nto actualy updating the member variable shaperOutI anywhere in that loop. So although you were emitting the signal and the QML backend was then in turn calling the property getter function, shaperOutIString(), that function was using the member variable shaperOutI which never changed from its default value of zero.

I have changed the last part of your loop to this:

@
/*
* print out the outputs of the filter for this loop iteration.
*/
cout.setf(ios::dec, ios::basefield);
cout << "Demod Shaper clock cycle " << i << ". ";
cout.setf(ios::hex, ios::basefield);
cout.fill('0');
cout << " iOut: " << setw(8) << getDemShpIOut() <<
". qOut: " << setw(8) << getDemShpQOut() << "." << endl;

setShaperOutI( getDemShpIOut() );

@

Note that I now rely on the setShaperOutI() function to emit the notifier signal - it also checks to make sure that the value really has changed.

As an alternative to this we could simple get rid of the member variable shaperOutI and change the getter function for that property to getDemShpIOut() however if that function does expensive calculations it is probably worth keeping it how it is with the shaperOutI member variable acting as a cached value.

With that sorted the application works fine. You can of course add a similar pair of properties for the quadrature variable and it shex representation.

The other problem I spotted (albeit a harmless one) was in the function setShaperOutI(long i). In here the call to shaperOutIString() is completely redundant as you do not do anything with the return value. This function then becomes:

@
void DemodShaper::setShaperOutI(long i)
{
if (shaperOutI != i) // only emit signal if value has changed
{
shaperOutI = i;
emit shaperOutIChanged();
}
}
@

The other thing I would change would be to alter the function:

@
long Soc::getShaperOutI()
{
return filter.getDemShpIOut();
}
@

to

@
long Soc::getShaperOutI()
{
return filter.getShaperOutI();
}
@

so that it uses the cached value rather than calculating it all over again when updating the QLabel. In fact thinking about it you could remove this function completely and call getShaperOutI() directly on the DemodShaperFilter object since you can get a pointer to it via the Soc class. ie:

@
void Widget::updateShaperOutI()
{
long shaperOutI = soc->demodShaper()->getShaperOutI();
QString s = QString( "shaperOutI = %1" ).arg( shaperOutI, FIELD_WIDTH, HEX_RADIX );
ui->label->setText( s );
}
@

Now you can add in similar properties for the quadrature values and pimp up the QML scene some more to impress your boss ;-)

Good luck!